IROC-Z_Racing

iTrader: (1)

without having to do any modifications to the wheel wells, what is the widest tire I can safely fit under my 89 IROC with a 17" wheel that won't rub the insides with the car lowered with Eibach Sportline Springs? Hammering the wheel wells out a little is fine IF it has to be done.

Thanks,
- Justin

xpndbl3

iTrader: (5)

some hammering a 275 would be fine. possibly 315 as well, but they typically start to stick out if you're not minitubbing.

IROC-Z_Racing

iTrader: (1)

thanks for that.

Cadillac

275's with ease at least on the rears.

Firebat

iTrader: (7)

Maybe 315 with hammer. This guy tucked his rear tires in an extra 1/2" and supposedly its possible to go another 1/2". These are 17x11 ZR1's with a 50mm offset and 1.5" wheel adapters:

https://www.thirdgen.org/forums/auto...ighlight=17x11

Cadillac

Oh yeah. THAT car.

Totally sick car and truly a TGO top 5.

FWIW, my wheels are 9.5 inches wide on all four corners.

krisb410

iTrader: (9)

I have 295s on 17 x 9.5, +56mm ZR1s with 2in spacers on the rear. 285s on 17 x 9.5s, + 56mm with 2 1/4in spacers up front. Not a single issue, but I have rolled my fenders because my car is lowered.

kerplunk318

iTrader: (3)

i used the 50 mm offset with a 1inch spacer but i also have an aftermarket rear, I barely beat the inner fenders. If you measure u can fit a 275 no problem, and a 315 with some effort. and you should definately roll those fenders if the car is lowered.

https://www.thirdgen.org/forums/susp...7x11-zr1s.html


Louis

iroczrockz

Hey do you think you would've had to roll your fenders if you used 275/40/17s with a lowered car? Just wondering what might be in store in the future. I found some 56mm ZO6 rims that are 17x9.5 but I want to lower the car a bit too. I have no idea what rolling the fenders involve or cost at a body shop. Also, what did those spacers cost you if you don't mind?

krisb410

iTrader: (9)

I rolled the fenders myself with a baseball bat, I got that idea from here, search for it. It was really, really easy, took just a few minutes, and didn't cost a thing!!! I'm not sure about 275s, but my 295s just barely hit the fender lip, so you might be ok without rolling the fender lip, but it's really super easy to do, so don't worry if you end up having to do it. I bought the spacers from www.skulte.com. I have a 4th gen LT1 rear that's ready to be swapped in, just haven't had the time/motivation to get it done yet.

Dr. Dirt

According to the March 2000 issue of Car Craft, the widest 17" wheel tire combo is: 17x9 wheel with 5 1/2" backspacing (both front and rear). Tires should have an aspect ratio of 40 or less. Maximum widths are 255 front, 275 rear.

krisb410

iTrader: (9)

Well, plenty of us here have proved that wrong.

Sonix

iTrader: (1)

Yea, for that wonderful butt-riding-on-a-skateboard feel

275/60/R15's here, with no work done Look up izcains car for some tall series tires, hahaha.

Dr. Dirt

Your experience may vary, I agree about the harsh ride of low-profile tires, I have 60 series tires and 15" wheels. Just thought published guidelines may help. You can fit 35x12.50 Mud Tires with "no modifications" as long as you don't mind torching the fenders!

Blownz28man

iTrader: (2)

I'm running zr1 wheels on mine..17x11w/315/35/17 rubber.I'm using a 1.25 spacer and looks sweet! 17x9 in front with 275 rubber. 1.5 spacer made the tires stick out to much

camarojustin

Why does everyone seem to think that low profile tires ride like crap?
Most people with low pros have done suspension mods (stiffer springs and/or lowering) That is what gives a stiffer ride. Most new vehicles have less of a sidewall than mine and guaranteed ride way better than a camaro with 60 series rubber. My tires are 255/40/18s front and 295/35/18 rear which is a 4" sidewall. A stock Iroc comes with 245/50/16s... a 4.8" sidewall.
Do you really think .8" difference in sidewall makes any difference at all?
With a 20 or 22 inch rim with a rubber band on it yes but an 18.. can't see it.

Sorry to get sidetracked. 275 on a 9.5" rim might get away without any mods but you should still expect that you may need to do a little. 295s, you will need to do some modification.

91_5.7_TPI

iTrader: (2)

My car has a LT1 rear end and 2" spacers in the front and I have 17x9.5s with 275/40ZR17s. Click on my sig pic for pictures.

Sonix

iTrader: (1)

I'm only giving my thoughts from my personal experience - as well as just some basic physics - smaller air cushion = harder.
My buddy put some rubber band tires on his 1985 V6 Camaro sport coupe, with zero other mods. Nice normal soft springs and shocks. I think they were something dumb like 205/35/R18 or something. R|ce tires.
If you have sufficiently wide tires (275 or greater) then 40 series would be ok, but for the skinny pinner tires, a small series makes them quite literally rubber bands. He thought the thing was great, for about a week. Driving it around was HARSH on the spine (not to mention my derriere), and it "skipped" like a rock on a pond, rather than a predictable slide like with his previous tires.

With 315's I sure wouldn't use 60 series, it'd be a monster truck tire, in that case i'd go down to 40-50.
But this really depends on what you're doing with the car eh? Drag racing - the larger diameter is good to offset steep gears, and taller sidewall helps absorb the shock of taking off. Autocross? With correct suspension then short sidewalls will grab the ground real nice. I just don't like it when people do it half-a**ed. ie putting on rubber band tires with stock suspension, or putting on super low lowering springs with stock tires shocks and rear suspension parts. Just replacing the visual part does not make the whole system work.

Boy, we really got sidetracked there eh Justin?

iansane

iTrader: (1)

Depends on the car, my bird didn't require any mods with fit 295/35-18's and verts have smaller shorter fenderwells than coupes.

BNBZ28

iTrader: (1)

i got a set of 325/50/15s to fit on mine yesterday. all you really need is to pound the lower part of the inner wheel well where the lca is and they will fit. drove them around and they didnt rub. they do stick out probly near 1/2 inch tho. thats on a weld draglite 15x10 w/ 5.5in bs.

AMH SCORPIO

what size rims and tires?

sprojam

this is probally the best post an closest to the trueth ive seen. im running p28540zr17s wheel 17bye 9.5 with 5.5 back space on the rear lowered 2in in front 1.5 rear an had to do some cutting an pounding an welding to get them not to rub on hard launches an corners. if you want to use spacers you can use the wider tires but then you are rollin fenders or just stickin out for plug an play go for the 275

chrisblazzer89

Who makes a decently priced 275/60/15 or 275/50/15?

91_5.7_TPI

iTrader: (2)

Are you talking about running a 275 on a 7 inch wide wheel?

chrisblazzer89

Im pretty sure my rear wheels are 15x8

krisb410

iTrader: (9)

My rear wheels are 17x9.5

91_5.7_TPI

iTrader: (2)

My car has 17x9.5s on all corners and I'm running 275/40s all around.
What wheels do you have? No 3rd gen wheels are 15x8s - they were 15x7s and 16x8s. Even if they were 15x8s, I don't think it would be safe to run a 275 on a 8" wheel. A 275 tire is almost 11 inches wide. That's alot of sidewall buldge.
But, if you want to try, go to tirerack.com. You'll be able to find about any tire made.

//<86TA>\\

iTrader: (15)

as for low profile tires riding like crap, my rears have an aspect ratio of 30 (335/30/18) and i dont think it rides bad at all. Its no cadallic, but i dont remember it being mush better back when the car was stock with 15x7's

Sonix

iTrader: (1)

Yea, 335 tires are so damn FAT even 30 series tires seem tall! They are probably as tall as your old 215/65's eh?? When I say "lo-pro" i'm talking about the clowns running around with 205/30 series tires. You know, rubber bands wrapped on the wheel? THOSE feel like riding on a skateboard. None of the fun of good handling due to crummy suspension, none of the cadillac feel, all of the filling-jarring experience. Yea, welcome back to the high school parking lot....

//<86TA>\\

iTrader: (15)

yea, the sidewalls are a hair taller than the fronts which are 245/40/18's.
I know what you mean about the real rubber-band tires, they must feels like driving on solid tires with no give at all. I cant imagine the rims would last long with those things

91_5.7_TPI

iTrader: (2)

My ex bought a Eclipse with a set of 18s that had 205/30s. That....was impressive lol